如何在MySQL中使用Python编写自定义触发器、存储引擎和触发器

import mysql.connector
from mysql.connector import errorcode

def create_engine(cursor):
    try:
        # 创建一个新的存储引擎
        cursor.execute("CREATE TABLE my_engine ();")
        cursor.execute("SHOW ENGINES;")
        rows = cursor.fetchall()
        for row in rows:
            if row[0] == 'MY_ENGINE':
                print('Custom engine created successfully.')
                break
    except mysql.connector.Error as err:
        if err.errno == errorcode.ER_TABLE_EXISTS_ERROR:
            print('Table already exists.')
        else:
            print('Error creating engine:', err.msg)

def drop_engine(cursor):
    try:
        # 删除自定义存储引擎
        cursor.execute("DROP TABLE my_engine;")
        print('Custom engine dropped successfully.')
    except mysql.connector.Error as err:
        print('Error dropping engine:', err.msg)

def main():
    try:
        # 连接到MySQL数据库
        cnx = mysql.connector.connect(user='root', passWord='password',
                                      host='localhost',
                                      database='my_database')
        cursor = cnx.cursor()

        # 演示创建和移除存储引擎
        create_engine(cursor)
        drop_engine(cursor)

        # 关闭数据库连接
        cnx.close()
    except mysql.connector.Error as err:
        print('MySQL Error:', err)

if __name__ == "__main__":
    main()

import mysql.connector
from mysql.connector import errorcode

def create_trigger(cursor):
    try:
        # 创建一个新的触发器
        cursor.execute("CREATE TRIGGER my_trigger BEFORE INSERT ON my_table FOR EACH ROW "
                       "BEGIN "
                       "IF NEW.column < 0 THEN "
                       "SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Invalid value'; "
                       "END IF; "
                       "END;")
        print('Custom trigger created successfully.')
    except mysql.connector.Error as err:
        if err.errno == errorcode.ER_SP_ALREADY_EXISTS:
            print('Trigger already exists.')
        else:
            print('Error creating trigger:', err.msg)

def drop_trigger(cursor):
    try:
        # 删除自定义触发器
        cursor.execute("DROP TRIGGER IF EXISTS my_trigger;")
        print('Custom trigger dropped successfully.')
    except mysql.connector.Error as err:
        print('Error dropping trigger:', err.msg)

def main():
    try:
        # 连接到MySQL数据库
        cnx = mysql.connector.connect(user='root', password='password',
                                      host='localhost',
                                      database='my_database')
        cursor = cnx.cursor()

        # 演示创建和移除触发器
        create_trigger(cursor)
        drop_trigger(cursor)

        # 关闭数据库连接
        cnx.close()
    except mysql.connector.Error as err:
        print('MySQL Error:', err)

if __name__ == "__main__":
    main()